INTERFACE PRESSURE PRODUCED BY THE TRACTION POST ON A STANDARD ORTHOPAEDIC

Abstract

The perineal traction post has been reported to cause pressure sores, skin necrosis, and pudendal nerve palsy. Tissue pressures of 70 mm Hg applied for two hours have been shown to result in microscopic tissue change whilst pressures of 1.4 kg/cm² for 90 minutes produced severe or complete nerve conduction block.

To demonstrate perineal traction post interface pressures. To assess effect of padding type on these pressures.

Healthy volunteers were positioned supine on the traction table with the right lower limb supported in flexion and abduction. Longitudinal traction of 40kg was applied to the left lower limb through the boot. Pressures were measured using a pressure pad consisting of individual calibrated inch square pressure cells. The pad was placed around the traction post. Five different types of padding were used on a standard traction post. These were: gamgee, small gel pad, 10cm gel bolster, 10cm soft foam roll and 10cm hard foam roll. With each device, the leg was positioned in neutral, internal rotation, external rotation and adduction. Pressure readings and pain scores were recorded with each manoeuvre.

Maximum pressures were experienced with the gamgee wrap. All subjects noted their highest pain score here. Peak pressures of 100 mm Hg were demonstrated over the ischial tuberosity and adductor tendons. The larger padding devices resulted in significantly lower pressures. Of the different positions, adduction was that which resulted in highest pressures and pain scores, though this was not significant.

The highest pressures exceeded the 70 mm Hg limit known to cause tissue damage. These pressures can be reduced with alteration of the padding. In all procedures it is important to pad the post carefully and use adducted positions for as short a time as possible.